1. Field of the Invention
The present invention relates, in general, to centrifugal extractors for extraction of an organic phase, including valuable elements such as platinoid elements, or the high radioactive elements, from the liquid radioactive wastes, thus preferably reducing the quantity of the radioactive wastes. More particularly, this invention relates to a structural improvement in such extractors to allow both a phase separation weir and a divert disk to be adjustable in their positions, thus effectively separating the organic phase from the liquid radioactive wastes.
2. Description of the Prior Art
A centrifugal extractor is widely used for the separation of an organic phase from an aqueous phase. In the conventional centrifugal extractor, both the height and thickness of a boundary layer between two phases vary in accordance with a mixing ratio of the two phases, as well as rotational speed of the mixed liquid as shown in FIGS. 2a to 2f. In addition, the reaction time of the two phases varies in accordance with the rotational speed of the centrifugal extractor. Therefore, to improve a saturation efficiency of such centrifugal extractors, it is necessary to adjust a height of a phase separating weir in accordance with a thickness of the boundary layer between two phases which varies with the mixing ratio. It is also necessary to appropriately control both the rotational speed and the reaction time of two phases.
However, in a conventional centrifugal extractor, the phase separating weir has a fixed height, so the extractor fails to deal a variation of the mixing ratio of the two phases. In this reason the satisfactory separation efficiency can not be obtained with the conventional extractor. So in the prior art, it is necessary to use a number of centrifugal extractors, having different rotational speeds in addition to separating weirs in different heights, to countermeasure the various mixing ratios of the phases. In addition, since it is impossible to adjust the height of the phase separating weir of the conventional extractor as desired, the liquid mixture has to be continuously rotated at a high speed until two phases are completely and parallely separated from each other as shown in FIG. 2d. In this case, the rotational speed of the centrifugal extractor should be set to a high velocity so that the reaction time of the two phases in the extractor is undesirably reduced. In addition, it is impossible to control the reaction time of the two phases as desired.
Accordingly, the present invention considers above problems in the prior art, and an object of the present invention is to provide a centrifugal extractor for effectively separating an organic phase from an aqueous phase of a liquid mixture, such as liquid radioactive wastes, which has an arbitrary mixing ratio of two phases by introducing height adjustable weir and divert disk. Thus, the extractor effectively recovers usable elements from the radioactive wastes while preferably reducing the quantity of radioactive wastes and finally conserving the storage capacity of radioactive waste.
In order to accomplish the above object, the present invention provides a centrifugal extractor, Being comprised: a liquid suction and rotation unit used for sucking the liquid mixture into the extractor, and separating the organic phase from the aqueous phase by rotating the mixture while adjusting the reaction time of the two phases; a height-adjustable separating weir unit used for locating the separating weir at a boundary layer between the two separated phases; and a housing unit used for supporting the liquid suction and rotation unit and providing the discharging paths of the two separated phases to the outside of the extractor, whereby the centrifugal extractor desirably separates the organic phase from the aqueous phase of the liquid mixture and desirably controls the reaction time of the two phases within the separator regardless of a variation of the mixing ratio of the two phases and/or a variation of the rotational speed of the separator.
The centrifugal extractor of this invention uses both a height-adjustable separating weir and a divert disk. The separating weir is installed between internal and external bearings. It is adjustable in its height in accordance with a thickness of the boundary layer formed between the organic and aqueous phases which varies with the mixing ratio of the two phases as well as the rotational speed of the mixtures. The centrifugal extractor of this invention is thus improved in its separation efficiency and allows a user to appropriately control the reaction time of the two phases. A divert disk, on which the two mixed phases collide to, is used for increasing the liquid flow speed in the centrifugal direction. This disk is mounted to an inlet tube and its height can be adjusted. Thus, it allows the user to appropriately select the reaction time of the mixed phases, by changing the liquid volumes contained between the divert disk and an impeller.